Open top compartments, such as truck trailers, dump trucks, storage bins and the like used for hauling or storing particulate material such as grain, ash, lime or the like are subject to having the materials fall or blow out onto the roadway. Similarly, relatively large loads of commodities such as lumber, plywood, building materials, building panels and the like on the beds of wheeled mobile carriers such as trucks, semi-trailers and full trailers are susceptible of dropping their loads onto the roadway with potentially disastrous consequences. With material such as gravel, aggregate or similar materials having portion of the load fall onto a roadway, is undesirable, both from the point of view of littering and the danger of material striking a following vehicle, possibly breaking a windshield or causing an accident.
Many localities now have laws requiring that all open top vehicle compartment be covered when containing loose or lightweight material. Often, the loads are simply covered with a tarpaulin that is tied to the edges of the open top at intervals around the opening. While sometimes effective, such tarpaulins are difficult for one person to put into place especially in windy conditions.
So called cargo tie-downs, also called hold downs or lashing straps, are commonly used in an attempt to control the hereinabove mentioned situations. These devices typically include a strap, bend or cord having a hook or loop at each end which enable the device to be connected to appropriate structures on a vehicle or trailer.
The strap, bend or cord is tensioned across the load to secure the load to the vehicle. Some of these devices have a generally resilient characteristic while other are substantially inelastic and include a ratchet, gear sets or buckle which allow the length of strap to be varied to secure the load on the vehicle.
Typically, the straps are drawn over the cargo, and each is applied to a winch mounted on the opposite side of the cargo bed. The winch can be turned in a direction to wind the strap tightly on the winch drum in order to tighten the winch straps on the cargo. A ratchet wheel and a pivotable pawl cooperate to lock the winch drum such that the straps are retained in a tight condition in which they are able to effectively restrain the cargo.
This type of restrain system used extensively throughout the transportation industry suffers from major drawbacks. The above described devices, such as the ratchet tie-down device, typically only uses a single ratchet, gear set or buckle to vary the length of the strap. While the single ratchet, gear set or buckle can be effective for securing some loads on vehicles, in some situations it can be desirable to have additional tension on the load which cannot be achieved using these devices. This is in part due to the known devices not providing a mechanical advantage to the strap, when tightened.
The single buckle, gear set or ratchet only have a single block for the strap between the end hooks and otherwise does not increase the user's mechanical advantage during the tie-down process. Moreover, some of these devices, and in particular the ratchet-type device, actually have a decreasing mechanical advantage as the device is being tightened which makes it even more difficult to tighten the device as the strap is pulled. That is why a rod is often used to act as a lever that a user forcibly pushes downward to tighten the strap and then ratchets up for another push downwards. If the gear set should break while the used pushes the lever downwards, he could seriously injure his knees or if there is a release of the pawl it could recoil the lever upwards thus potentially causing injury to the upper body of the user such as the face. Furthermore, because of the strength require to properly tighten a load, there is an increased risk of repetitive stress injury to the back and shoulders.
Another disadvantage associated with prior art devices relates to the fact that no provision has previously been made to disengage the pinion gear from the drum gear. In other words the gears are permanently meshed. As a consequence, when an operator pays out line, that is unwind the lines from the drum by pulling the line, the drum turns and drives the pinion gear which in turns spins the handle. If the line is quickly payed out, the handle spins both rapidly and forcibly, which is another potential cause of injury.
Another main drawback associated with most conventional winch for cargo tie-down straps, relates to the fact that they are both non ergonomical and tedious to operate. Furthermore, they are often mechanically complex and thus susceptible to break down in the sometimes harsh transportation environments.
Accordingly, there exists a need for an improved winch for cargo tie-down straps.